Morgan Freeman had it right in the first “RED” installment when his doomed character grinned at fellow retired black-ops agents Bruce Willis, John Malkovich, and Helen Mirren and said, “We’re getting the band back together. That’s nice.” It was sort of nice, an “Expendables” alternative with some actual wit. No matter that this particular celebrity klatch didn’t really have any shared industry history — they seemed to be having effortless fun. We even got to see Malkovich, as a paranoid nutjob, slumming in a role that, for a change, wasn’t just embarrassing.

But you know how it is with those band reunions. There’s the charge you get from seeing your old faves back together onstage — then they hit it off OK, and decide to do a new album. And another couple of tours. Inevitably it’s all a little less cool. So it goes with “RED 2,” a sequel that has some snappy interplay, typically courtesy of Malkovich, but mostly feels like a cast working to manufacture what came naturally the first time.

The follow-up opens by teasingly defanging the title’s “Retired: Extremely Dangerous” designation, with Frank Moses (Willis) now content to be out of action, and happily bargain-hunting at Costco. His girlfriend, Sarah (returning Mary-Louise Parker), is the one yearning for excitement, an itch that’s scratched when Marvin (Malkovich) turns up warning them that they’re all being targeted in a new conspiracy. Seems Frank and Marvin have been falsely implicated in a decades-old nuke-smuggling plot, and they need to jet off to Paris, Moscow, and London to deal with the bounty on their heads and locate that long-hidden bomb.

In the early going, it’s a kick. Malkovich has a funeral scene that plays like “Tom Sawyer” with hit-man humor. Journeyman director Dean Parisot (“Galaxy Quest”) choreographs some creative action — imagine, Pringles as a motion detector! — for a sequence that has Willis scrambling to elude a relentless government heavy (underutilized, piercing-eyed Neal McDonough). Malkovich hilariously blurts out a profane torture scenario preferable to the fugitive stress they’re under.

And then, all too quickly, everything turns labored. Catherine Zeta-Jones grows bangs to convince us she’s a sexpot Russian agent — and Frank’s longtime Kryptonite, as we’re told. But her main contribution is to create contrived tension between Sarah and Frank that just steps on Parker’s likable quirkiness as this character. Mirren gamely spoofs “The Queen,” but you’d guess the gag worked better on the page. Anthony Hopkins turns up as the addled uber-Oppenheimer originally behind the nuke, but he’s disappointingly flat. Byung Hun Lee (“G.I. Joe”) gets a couple of entertaining moments as a nasty Korean contract killer, and a bunch of noisily superfluous ones.

If only the vibe felt as loose as before. Reprising his role as Mirren’s Soviet paramour, Brian Cox elicits a laugh — and a cringe — for one particularly odd display of fetishy adoration. We could do with more of this brand of weirdness. Instead, we have to be satisfied with the buff’s diversion of seeing two former Hannibal Lecters share the screen. (Cox, you’ll recall, starred in “Manhunter.”) Maybe they can have Mads Mikkelsen pile on for “RED 3.”